I can't tell if you're being sarcastic, but it's not an odd coincidence. It's an explicit response to Musk's Nazi salute.

A full day seems like a pretty reasonable timeframe for something big to spread on social media (I'm not even gonna touch however you're trying to connect this to BLM). Reddit mods are probably literally some of the most "online" people imaginable so once something is on the front page in one or two major subreddit they are gonna be aware within a couple hours, idk why anyone would think this would need even 24 hours to spread

I think you’re looking for a conspiracy that’s just not there.

It’s just people seeing an idea and jumping on the bandwagon. Plus, if you look at lots of the threads, there are already a pent-up dissatisfaction with the user experience of links to X, so the door was partly open.